Add Overlay/Watermarking and option to use local FFMPEG

[TheSin-]

This PR does lots, still a WIP but wanted it documented so others can see progress

TODOS

• [x] Add docker or local ffmpeg as a switch (making docker optional)
• [x] Add Overlay/Watermarking to the stream
• [x] Add many more options to the settings allowing for more configuration of the ffmpeg command for experts
• [x] Add detection of local ffmpeg otherwise disable the option and force docker Use system ffmpeg command location when not using docker
• [x] Add proper messages if system webcam url or ffmpeg command is blank
• [ ] Test webcam stream to make sure it's accessible before using it
• [x] Add select for watermarks or overlays to use
• [x] Add method to upload watermarks or overlays
• [x] Add method to delete watermarks or overlays
• [x] Add way to setup info that can be injected into the overlay, layer height, ETA, etc (as long as Octoprint has a value we should be able to display it). This is complex as we will need to have positions for each piece of data.
• [x] Decide if /dev/shm is a saner place then /tmp, for RPi it will save lots of read/writes to the SD
• [x] use os.path.join instead of str concat with / s
• [x] test for Darwin, win32 and if linux check if we are a pi to build presets to make plugin platform independent, or at least compliant

Known Issues

• [x] Reload available files in the settings drop down when the settings page is loaded
• [x] Coords on a new Dynamic Setup line show 0,0 until the settings are reloaded, this shouldn't happen.

[jneilliii]

Instead of /tmp/ I think we should use /var/run as I've recently learned is stored in memory on raspberry pi OS instead of on sd card. That will reduce writes and prolong the life of the sd card.

[jneilliii]

Replace self._basefolder + "/static/img/" with self.get_plugin_data_folder(). This will allow uploaded files to be backed up with octoprint.

[TheSin-]

both great suggestions, I'll work on changing that up right away

[TheSin-]

Maybe I'll make the tmp dir an option as /var/run will likely yield perm issues, specially on other platforms?

[TheSin-]

just as I suspected for /var/run

$ touch /var/run/test
touch: cannot touch '/var/run/test': Permission denied

it's not good form for linux to do that either. But I do understand due to the SD card, I run my entire /home/pi on USB drive instead to save my SD. We could maybe setup a ramfs and mount it, or use overlayfs which is held in mem if we are super worried about it. We could also put a warning on it for pi users ? Thoughts?

/run/user is an option as it'll have user perms, we'd have to use the env var for it though

XDG_RUNTIME_DIR=/run/user/1000

and that still isn't a guarantee as it's XDG specific and wouldn't work on MacOS or other linux installs for sure.

/dev/shm is an other tmpfs on pi. it's user writable, but it's not in good linux fashion to use it as a tmp, but it would achieve what you are looking for.

Filesystem      Size  Used Avail Use% Mounted on
/dev/root        32G  5.9G   25G  20% /
devtmpfs        423M     0  423M   0% /dev
tmpfs           458M     0  458M   0% /dev/shm
tmpfs           183M  619k  183M   1% /run
tmpfs           5.3M  4.1k  5.3M   1% /run/lock
/dev/mmcblk0p1  265M   52M  213M  20% /boot
tmpfs            92M     0   92M   0% /run/user/1000

and I take /run/user back as that will only be available while pi user is logged into a console so that won't work even if we could figure it out. So the only option is /dev/shm but it's really not a great idea to put files in to the shm dir

[jneilliii]

I'm not super familiar with any of this linux based stuff, just know that it can be a problem writing a bunch and if we're saving an image every 2 seconds that seems like it could be a lot. I'm going to ask over on the dev-plugin channel in Discord and see what the consensus is.